That's great thank you very much for your help

Perfect, thank you, that works. I overlooked this because the docs said "ELEMENT" is the default behaviour so I assumed this was also the case for collection properties.

We're still using Healthshare 2017.2 unfortunately. Do you know if there is anything similar for our version?

That's perfect thank you. To answer your and Enrico's question - I'm working against a FHIR spec and series of examples which present it in this way, so to avoid any potential problems I'm trying to match these as much as possible. It may be valid XML but I'm not taking any chances!

Perfect! The source code for that class method is exactly what I need, thank you.

Just for others who have the same problem, you can do the following:

do $System.Encryption.MD5HashInit()
do $System.Encryption.MD5HashUpdate(stream.Read(...)) // Read in each chunk stream
set hash = $System.Encryption.MD5HashFinal()
set checksum = $ZCONVERT(##class(%xsd.hexBinary).LogicalToXSD(hash), "L")